# Lib configurations

- **Type:**

```ts
interface LibConfig extends EnvironmentConfig {
  format?: Format;
  bundle?: boolean;
  autoExtension?: boolean;
  autoExternal?: AutoExternal;
  redirect?: Redirect;
  syntax?: Syntax;
  externalHelpers?: boolean;
  banner?: BannerAndFooter;
  footer?: BannerAndFooter;
  shims?: Shims;
  dts?: Dts;
  umdName?: string;
}

interface RslibConfig extends RsbuildConfig {
  lib: LibConfig[];
}
```

- **Default:** `undefined`

- **Required:** `true`

The `lib` configuration is an array of objects, each representing a distinct set of configurations. These include all Rsbuild configurations as well as Rslib-specific configurations, designed to generate different outputs.
